trip cord vs tripline

trip cord

noun
  • A cord, line, lanyard, or wire that, when pulled, mechanically activates a device. 

  • A type of electrical extension cord: see pad. 

tripline

noun
  • A concealed wire or string that sets off an alarm or activates a trap when tripped. 

How often have the words trip cord and tripline occurred in a corpus of books? (source: Google Ngram Viewer )